In producing a compact disk (DVD), two DVD substrates are glue-laminated and exposed to ultraviolet for setting the glue. One of the two DVD substrates has a laminating surface being coated with recordable laminae, while the other DVD substrate is transparent and has a laminating surface without any coating.
In a conventional way for laminating the two DVD substrates, first apply one circle of glue on the laminating surface of one substrate, and then flatly lay the other substrate to the top of the glue-applied substrate, so that the two substrates are laminated. This is the so-called one-surface glue lamination.
As it is known, glue is a positive-ion ultraviolet-hardening compound, and is a material completely different from that for forming the transparent and the laminae-coated substrates. Therefore, when the glue is compressed between two DVD substrates, it is forced to spread between and contact with two different media. Due to the problem of spray galvanizing, the glue flows in unstable directions to result in uneven distribution of the glue. In a severer condition, blisters are produced to form defects in the manufacturing process.
It is apparently desirable to develop an improved DVD manufacturing machine to eliminate the problems existed in the conventional way of producing a compact disk through one-surface glue lamination, and to increase the rate of good yield of completed compact disks.